450SL - how to determine functionality of climate control

[supercanuck]

Hey guys, I have made a few posts before about my climate control, as I'm trying to get to learn it and fix everything that has resulted from my broken servo.

As of now, I have removed my servo and bypassed the hot water valve, and in the process I fried my amp, so basically all I'm getting is hot water going into the core. However, before I start working with installing new valves, etc, I want to make sure that the major components of my climate control (compressor on/off, push buttons, etc) are working properly.

How can I go through and test the major components of the climate control to figure out what is and isn't working, so I can try to figure out a starting point in getting it back up and running?

Thanks!

[450slcguy]

Originally Posted by supercanuck

How can I go through and test the major components of the climate control to figure out what is and isn't working, so I can try to figure out a starting point in getting it back up and running?

Buy the CD, it has a whole section devoted to climate control function and testing.

[supercanuck]

Cool. I've actually got it, so I'm trying to get through it and understand it.

Another quick question...Can the compressor run without the amp and servo?

[UT_Tech]

You sure can. There's a vacuum switch which enables the AC compressor which is driven from the same vacuum "circuit" (the BLACK vacuum line) as turns on the vacuum switch for the blower. If the blower is working, the AC compressor should be able to run.

If you have the CD set you can find the wiring diagram. The following switches control the AC compressor:
1. Vacuum switch, mentioned above
2. Switch on the control panel, On/Off
3.ETR switch, that the switch on the evaporator box (behind the glove box liner) which turns off the AC compressor if the evaporator freezes over.
4. Low refigerant pressure switch.

If all the switches are OK then the AC compresor will run. At idle the air coming out of the center vents should be 50F or less. Use a supermarket food thermometer, don't guess at the temperature.

[notillr]

nm

[UT_Tech]

For whatever reason the 116 chassis manual is available on the web:

http://handbook.w116.org/matrix6.htm

The AC system on a 1980 300SD is nearly identical to yours. The electrical system is identical. PM me if you have trouble reading the electical diagrams.